|Publication number||US8175426 B2|
|Application number||US 12/610,432|
|Publication date||May 8, 2012|
|Filing date||Nov 2, 2009|
|Priority date||Nov 2, 2009|
|Also published as||CA2778877A1, CN102597834A, EP2496980A1, EP2496980B1, US20110103741, WO2011053862A1|
|Publication number||12610432, 610432, US 8175426 B2, US 8175426B2, US-B2-8175426, US8175426 B2, US8175426B2|
|Inventors||Lawrence Wayne Shacklette|
|Original Assignee||Harris Corporation|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (33), Non-Patent Citations (3), Referenced by (3), Classifications (16), Legal Events (1)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The present invention relates to the field of optical waveguides and optical fibers, and, more particularly, to optical fiber connectors, waveguide devices, and related methods.
Optical fibers are commonly used in telecommunications for communicating data signals over both short and long distances. With respect to other communication mediums, such as metal wires, optical fibers are advantageous in that signals travel along them with less loss, and they are also less susceptible to electromagnetic interference. Optical fibers also enjoy very high bandwidth (i.e., data rates). Optical fibers may also be used for illumination, and may be wrapped in bundles and used to carry images, such as in fiber optic cameras. Optical fibers may also be used in other applications, such as sensors and lasers, for example.
One disadvantage of optical fibers, however, is that they are more difficult to couple together than wire conductors, as discontinuities at a connection point can lead to light reflection and losses that significantly degrade signal quality. One approach to joining optical fibers is the use of mechanical fusion splicers, which align and fuse two fiber ends together. While this provides a very low loss connection between the fibers, fusion couplers are typically very expensive, and thus not practical for many implementations. Fusion splicers form permanent connections and are less suitable for temporary splices or other connections that are to be made temporary or dynamic.
Another approach used in some optical interfaces is to apply an index-matched material, such as liquids or gels. While such materials may generally be formulated to match the index of refraction of an optical medium, problems may arise due to migration of the index-matched material and contamination in unwanted areas. Moreover, such materials are prone to attract dirt, and are typically difficult to clean once contaminated.
U.S. Pat. No. 5,778,127 to Gilliand et al. discloses an optical transceiver apparatus which has a housing including a diode package aligned with a lens, and having an optical filler composition injected therebetween. The optical filler composition comprises a silicone elastomer which may be used as an index matching element, as a positioning and locking means, or an optical attenuator. Other exemplary approaches for optical fiber connectors or terminations are set forth in the following references: U.S. Pat. No. 5,619,610 to King et al.; U.S. Pat. No. 5,515,465 to Olin et al.; U.S. Pat. No. 6,501,900 to Aloisio, Jr. et al.; U.S. Pat. No. 6,097,873 to Filas et al.; and U.S. Pat. No. 5,058,983 to Corke et al.
In view of the foregoing background, it is therefore an object of the present invention to provide an optical fiber switch and related methods providing enhanced optical interconnection.
This and other objects, features, and advantages are provided by an optical fiber switch which may include first and second angled optical fibers having respective first and second end faces. Each of the first and second angled optical fibers may include a core having a core index of refraction, and a cladding surrounding the core and having a cladding index of refraction different than the core index of refraction. The optical fiber switch may further include a first index matching elastomeric solid layer having a proximal face coupled to the first end face, and a distal face opposite the proximal face to be repeatably optically coupled to the second end face. The first index matching elastomeric solid layer may have an index of refraction profile matching an index of refraction of the core and the cladding. The optical fiber switch may also include at least one actuator for relatively moving the first and second angled optical fibers between a coupled position and an uncoupled position. As such, the optical fiber switch is thus relatively durable and provides desired optical coupling properties.
More particularly, the proximal end face may be chemically bound to the first end face, and the distal end face may be low-tack to be repeatably directly mechanically coupled to the second end face. Moreover, the low-tack distal face of the first index matching elastomeric solid layer may have surface properties defining a wetted interface devoid of air pockets with the second end face when pressed thereagainst. In addition, the optical fiber switch may further include a second index matching elastomeric solid layer having a proximal end face chemically bound to the second end face, and a low-tack distal face opposite the proximal face to be repeatably optically and mechanically coupled to the low-tack distal face of the first index matching elastomeric solid layer.
By way of example, the first angled optical fiber may include a first pair of transverse optical fiber ends joined together, and the second angled optical fiber may include a second pair of transverse optical fiber ends joined together. Also, the first index matching elastomeric solid layer may comprise an acrylate polymer, for example.
In some embodiments, the first end face may have a canted angle from perpendicular to an axis of the first optical fiber, and the first index matching elastomeric solid layer may have a uniform thickness and match the canted angle. By way of example, each of the first and second angled optical fibers may comprise a multimode optical fiber, and the at least one actuator may comprise at least one piezoelectric actuator.
Furthermore, the first index matching elastomeric solid layer may have a central region having a first index of refraction matching the core at a desired operating wavelength, and a region surrounding the core having a second index of refraction matching the cladding at the desired operating wavelength. The first index matching elastomeric solid layer may also have a central region having a first graded index of refraction matching the core at a desired operating wavelength, and a region surrounding the core having a second index of refraction matching the cladding at the desired operating wavelength.
A related method for making an optical fiber switch may include forming first and second angled optical fibers having respective first and second end faces. Each of the first and second angled optical fibers may include a core having a core index of refraction, and a cladding surrounding the core and having a cladding index of refraction different than the core index of refraction. The method may further include forming a first index matching elastomeric solid layer having a proximal face coupled to the first end face, and a distal face opposite the proximal face to be repeatably optically coupled to the second end face, where the first index matching elastomeric solid layer may have an index of refraction profile matching an index of refraction profile of the core and the cladding. The method may also include positioning at least one actuator for relatively moving the first and second angled optical fibers between a coupled position and an uncoupled position.
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout, and prime notation is used to indicate similar elements in alternate embodiments.
Referring initially to
The first index matching elastomeric solid layer 40 also advantageously has an index of refraction n1 matching at least the index of refraction n1 of the cores 35, 36. That is, the index of refraction of the first index matching elastomeric solid layer 40 is chosen to be substantially the same as that of the cores 35, 36 to be coupled together. This first index matching elastomeric solid layer 40 advantageously provides the optical function of an index matching liquid or gel, but without the above-noted disadvantages of such materials (e.g., less susceptible to contamination, etc). Further, by chemically bonding the first index matching elastomeric solid layer 40 to the first end face 41, the layer may thereby remain permanently in place while temporary connections are repeatedly made with the second mating end face 34.
As a result of its index matching, elastomeric solid properties, and chemical bonding to the first end face 33, the layer 40 advantageously provides reduced transmission loss and back reflection. Moreover, it also remains in place indefinitely, and does not migrate as do index matching gels and liquids. Additionally, the layer 40 may be more resistant to dirt and contaminants and may be cleaned, it retains an optically smooth surface, may be cast or formed into desired shapes, and it may be tailored to a wide range of refractive index values and elastic properties (e.g., modulus, flexibility, etc.), as will be appreciated by those skilled in the art. By way of example, the first index matching elastomeric solid layer 40 may comprise an acrylate polymer. Because acrylates may be patterned using lithography, for example, they provide the ability to form precise layer structures shaped and positioned with a relatively high degree of accuracy. Further details regarding exemplary elastomeric formulations that may be used for the layer 40 will be discussed further below.
In some embodiments, the low-tack distal end face 42 may be repeatably directly mechanically coupled to the second end face. For example, the low-tack distal face of the first index matching elastomeric solid layer may have surface properties defining a wetted interface devoid of air pockets with the second end face when pressed thereagainst, thereby providing in part a mechanical suction coupling with the second mating end face 34 of the second optical fiber 32, as will be appreciated by those skilled in the art.
In the illustrated embodiments, the optical fibers 31, 32 are multimode fibers. That is, the optical fibers 31, 32 may advantageously support many propagation paths or transverse modes, as opposed to single mode fibers which support a single mode or propagation path. Multimode fibers generally have a larger core diameter, and are used for short-distance communication links and for applications where high power transmission is required, such as in localized networks or between buildings. As such, since the addition or replacement of optical fibers may be more prevalent in localized areas where multimode fibers are used, the ability to repeatably optically (and, optionally, mechanically) couple multimode fibers may be a significant advantage. However, it will be appreciated by the skilled artisan that index matching elastomeric solid layers as described herein may also be used with single mode optical fibers, which are typically employed for relatively long communication links.
Referring now additionally to
As shown in
The layer 40″ is tailored to form an extension of the optical fiber 31″, and to conform to the angle of the end face of the fiber. A high degree of light transmission may advantageously be maintained between the two optical fibers 31″, 32″ as a result of the layer 40″, whereas without this layer little or no light would be transmitted therebetween. Moreover, the elastomeric nature of the layer 40″ advantageously allows small discontinuities in the mating faces to be uniformly filled, thus reducing the loss of light through reflection and scattering at the interface, as will be appreciated by those skilled in the art.
Yet another embodiment of the repeatable optical fiber interconnection 30′″ is now described with reference to
A related method of making a repeatable optical fiber interconnection between the first and second optical fibers 31, 32 is now described with reference to
Turning now to
As also noted above, acrylates and copolymers with urethanes and thiolenes are advantageous materials for forming the layer 140, as they may provide desired optical matching and may be precisely patterned using techniques, such as lithography or molding, with a relatively high degree of accuracy. Moreover, these materials may advantageously be used to create different index profiles for the first portion 148. More particularly, an alternative embodiment of the layer 140′ is shown in
Another method of making a repeatable optical fiber interconnection between the first and second optical fibers 131, 132 is now described with reference to
An exemplary approach for forming the layer 140 with the first and second portions 148, 149 will now be discussed with reference to
If a graded index is desired, the core or first portion 148 may be partially cured to a level sufficient to define the core, and the liquid cladding formulation may be allowed to exchange monomers with the core by allowing the assembly to soak at some elevated temperature (e.g., 40 to 60° C., although other temperatures may be used in different embodiments), at step 114. The degree of grading will depend on time, temperature, and the percentage of cure in the patterned core, as will be appreciated by those skilled in the art. In general, for a graded index guide it is desirable that the monomers in each formulation include two or more monomers that have relatively widely spaced refractive indexes and differing rates of cure, allowing monomers that have different refractive indexes to be readily diffused into and/or out of the core region, as will also be appreciated by those skilled in the art.
If a thermal soak is not being used to provide a graded index, the injected clad formulation may simply be allowed to stand at room temperature for a sufficient amount of time to allow the cladding portion 149 to spread around the core portion 148. A second UV exposure may be performed at step 115, after which the layer 140 may remain bonded on the substrate for packaging or handling, at step 116, or removed from the substrate 116 to provide a free standing layer to be coupled to the optical fiber 131, at step 117. In accordance with one exemplary implementation, the layer 140 may be peeled from the substrate 109 while still attached to the glass cover plate 113. A mask size of 62.5 microns in diameter was used in one exemplary implementation, and this diameter was essentially reproduced in the size of the core. Deviations in the diameter may advantageously be produced by under or over exposure or by under development, if desired, as will be appreciated by those skilled in the art.
Additional configurations that may be produced using variations of the above-described approach are illustrated in
Referring now to
Each of the first and second angled optical fibers 201, 202, illustratively includes respective first and second end faces 203, 204. As with the above-described embodiments, an index matching elastomeric solid layer 240 is included and has a proximal face coupled to the first end face 203, and a distal face opposite the proximal face to be repeatably optically coupled to the second end face 204. Here again, the index matching elastomeric solid layer 240 has an index of refraction matching the index of refraction of the core, as shown in
A related method for making the optical fiber switch 230 is illustrated in
In some embodiments, the optical switch may include an index matching elastomeric solid layer matching both the core and the cladding, as discussed above with reference to
Generally speaking, desirable characteristics of a multimode switch include achieving stringent requirements of low insertion loss, low return loss, and fast switching time. However, such characteristics are generally difficult to achieve in a multimode switch. Typically, multimode switches are of a mechanical type utilizing moving fibers or moving optical elements (e.g. mirrors). Achieving the fast switching time requires micro-electromechanical systems (MEMS) scale components to reduce the moving mass. Designs that reduce the extent of the required motion also are desirable. Moreover, precise alignment of the switch in the coupled switch state, angling of the waveguide faces, and/or careful index matching within the interface between guides are also typically desirable. Reduction of any unguided light paths is also a significant consideration.
These characteristics may advantageously be achieved with the switch 200, which operates on the principle of frustrated total internal reflection (FTIR). The switch 200 requires only a short degree of motion between the first and second end, faces 203, 204. Generally, the required displacement need be only about 3 wavelengths (e.g., 4 microns) or less to operate the switch 200. The switch may be designed with a 45-degree or greater angle (α) interface, so that back reflection in state 1 (coupled position) will be strongly suppressed. As noted above, the switch 200 may accomplish either of two switch states, namely (1) A to A′ (i.e., coupled) and (2) A to B and/or B′ to A′ (uncoupled). The switch 200 may be built as a half 2×2 crossbar switch, or it may be assembled from two 1×2 switches, as will be appreciated by those skilled in the art.
Exemplary optical fiber switch implementations will now be described with reference to
In those embodiments where the core region 148 of the SIMM may also be graded in index, light is advantageously allowed to propagate through the EIMM just as it does through the fiber itself. This provides for reduced loss, and allows the EIMM to be of different thicknesses as needed to satisfy the mechanical aspects of the given design. In state 2 (i.e., uncoupled), a significant portion of the light will be reflected at the interface between the EIMM and air. As will be appreciated by those skilled in the art, variations of the basic design shown in
Various EIMM polymer formulations may be used for the repeatable optical fiber interconnection and optical fiber switches discussed above. Generally speaking, the EIMM polymers may be formed through UV curing of acrylates and/or methacrylates. Fabrication of the polymer may begin with a formulation of liquid acrylate and/or methacrylate (abbreviated herein as (meth)acrylate) monomers with a small amount of a photoinitiator and an antioxidant. The index of refraction of the monomers at 589.3 nm (sodium D line) is provided by the manufacturer. For optical fiber applications, the index of the polymer at 1310 nm and/or at 850 nm is of particular interest. Polymers made with different monomer formulations will have both a different index and a different dispersion, as will be appreciated by those of skill in the art.
An initial estimate may be used to determine the refractive index as a function of the relative amounts of the monomers in the starting formulation. This estimated formulation may be used as a starting point, and then small additions of specific monomers may be used based upon actual measurements to refine the targeted refractive index formulation for the desired polymer.
Table 18.1 provides input values describing the characteristics of the liquid monomers and the volume percentages of each monomer that are targeted for use. The empirical parameters in the first two columns of Table 18.3 give a measure of expected change to be incurred as a result of polymerization (δ), and the expected shift in the index in going from 589 nm to 1310 or 850 nm as a result of dispersion (ξ). δ is estimated by the ratio of index at 589.3 nm between the liquid monomer and the cured polymer. The dispersion factor, ξ, is the ratio of the index of the polymer at the target wavelength (850 or 1310 nm) and the index at 589.3 nm. These parameters are obtained from measurements on closely related acrylate polymers. The calculated values are highlighted in the last three columns of Table 18.3. In the illustrated example, the NA of Corning InfiniCor SX 50-μm fiber is 0.200, so the volume percentages of the various monomers are adjusted to reach this value. The calculation of the expected refractive index is made with Eq. (1) below, where Vfi represents the volume fraction of the ith component, δ is the polymerization factor, and ξ is the dispersion factor at 1310 or 850 nm:
n polymer=(n A *Vf A +n B *Vf B +n C *Vf C +n D *Vf D +n E *Vf E)*δ*ξ (1)
Exemplary switches were designed around two graded-index fiber types: InfiniCor SX (50 μm) and Corning InfiniCor CL-1000 (62.5 μm) from Corning, Inc., of Corning, N.Y. Systems operating at 850 nm would tend to use InfiniCor SX, while those operating around 1310 nm would tend to use InfiniCor CL-1000, although either fiber type may be used within either wavelength region. Since the EIMM is designed to provide index matching, it is significant to characterize the index of refraction of the respective fibers at the wavelengths of interest, and a summary thereof is provided in the following table of measured and specified parameters for Infinicor fibers.
InfiniCor CL 1000
As discussed above, the elastomeric index matching medium may be a (meth)acrylate polymer that is synthesized from acrylate and methacrylate monomers by UV curing. Monomers are selected on the basis of a variety of criteria covering the desired properties of the polymer, such as refractive index, hardness, modulus, toughness, and clarity, as will be appreciated by those skilled in the art. Monomers having lower health risks or toxicity may also be favored. Polymers of low to moderate hardness are also generally desirable, so that effective wetting of the optical contact surface may be readily achieved when the switch is in the closed or coupled (A-to-A′) position. The modulus will determine the force necessary to achieve a wetted spot covering the entire core (and optionally cladding) region of the fiber.
One exemplary selection of acrylate monomers is shown in
The above-noted monomers include both monofunctional and difunctional monomers, that is, they contain either one or two (meth)acrylate groups. These groups are subject to a free-radical polymerization mechanism that leads to a heavily crosslinked solid that has elastomeric properties. To initiate polymerization with UV light, a UV-sensitive photoinitiator is included in the formulation. Also, to reduce the tendency to yellow with age, an antioxidant is added. Each of these components is present only as a small percentage of the formulation, e.g., at a 2% or lower level. As already noted, one desirable aspect of the formulation is that constituent components are miscible, and remain so as polymerization occurs. Phase separation may lead to haze formation, and thus optical scattering loss. Exemplary formulations are listed in the table below:
Elastomeric Index Matching Material Formulations
bisphenol A diacrylate
Additives taken as a percent of the total of the materials list
By way of example, Irganox 1010 from Ciba of Basel, Switzerland may be used as a suitable antioxidant. Moreover, two suitable liquid photoinitiators are shown in
Several material formulations made with the above monomers and photoinitiators were characterized in terms of their index of refraction and dispersion characteristics. Samples of core and cladding were coated on a silicon substrate and exposed to a dose of 1500 mJ of UV light from a high-pressure mercury light source that outputs approximately 35 mW/cm2. The cured samples were then annealed under flowing nitrogen for 1 hour at 125° C. The annealing procedure has the potential to sublime away any low molecular weight species, such as residual uncured monomer and the photoinitiators. The refractive index was measured by a prism coupling measurement on thin films (typically 10 to 50 microns in thickness). Results for the formulation designated EIMM-200 from
As noted above, it may be desirable to design the mechanical properties of the EIMM to match the characteristics needed for the given switch. For example, measurements may be made on the materials formulated using a Differential Scanning Calorimeter (DSC) to determine glass transition temperature (Tg), and a Dynamic Mechanical Analyzer (DMA) to determine storage modulus. These values, along with refractive indexes, are recorded in the following table. The data demonstrates that the mechanical and thermal properties may be varied over a very large range through the choice of different recipes for the monomer formulations.
Measured Characteristics of Acrylate Polymer Films(1)
9.3 to 60(4)
(1)Solid polymer after anneal at 125 C. for 1 hr under nitrogen.
(2)Tg determined from 1st heating in Differential Scanning Calorimeter (DSC)
(3)Modulus from Dynamic Mechanical Analysis (DMA)
(4)Range depending on cure and thermal history
Monomer Formulations for Selected Elastomeric Solids
The EIMM structure or layer may take various forms, one of which is a layer of material that has an index equaling the effective index of the fiber. Again, the EIMM is advantageous over liquid index matching materials in applications such as those shown in
To fabricate the waveguide on the end of a fiber, the 50-micron core fiber may be angled at 51 degrees to provide total internal reflection at the fiber end for the supported light rays. The waveguide may be coaxial with the fiber. One exemplary fixture 300 for creating this geometry is shown in
After the core exposure, the structure may be developed using a solvent mixture of methanol and isopropanol, for example. A second mask (not shown in
Exemplary thicknesses which may be used for the EIMM layer 340 in optical fiber switching and interconnection applications may be in a range from about 25 μm to 75 μm, for example, although other thicknesses may also be used. For such thicknesses, a 1-μm deformation of the layer 340 upon closure of the switch will result in a strain that lies between about 4% and 1.3%, respectively. It should be noted that the effective hardness of the layer 340 will be related to the thickness, since for such thin films the hardness of the substrate influences the effective hardness of the polymer.
The EIMM layer 340 may advantageously conform to irregularities at the interface of two temporarily conjoined optical fibers to reduce reflections or scattering losses. A test for pairs of fibers polished at a 45-degree angle was performed which validated this function. For the test, the EIMM polymer was grown on the surface of a fiber polishing block in the shape of a 1 mm×1 mm pad that covered the fiber end. A second fiber also held in its polishing block, but not covered by EIMM, was then used to make an optical connection to the first fiber. This connection was achieved through active alignment, and the minimum transmission loss and maximum reflection loss as measured with an optical time-domain reflectometer (OTDR) were recorded. The test employed Corning InfiniCor CL 1000 62.5-μm fiber. For the test there was no guide structure in the EIMM layer, just a continuous coating of an EIMM material that matched the peak index of the graded index fiber, as will be appreciated by those skilled in the art.
Data taken with various thicknesses of the EIMM are presented in the following table:
Measured and calculated loss for 1310-nm light transmission through a gap filled with EIMM Calculated Loss Separation for 62.5 Fiber Data * @ 1310 RL (μm) (dB) (dB) (dB) 5 0.034 10 0.068 25 0.173 0.175 59 50 0.353 0.306 71 100 0.738 1.037 75 * Using pad of EIMM-12 Core of thickness (s)
As may be seen, desirable return losses may be achieved (e.g., greater than 70 dB). For the thinnest sample, it is theorized without wishing to be bound thereto that the blocks may not have been sufficiently parallel to allow full approach and optimization of the RL. It should also be noted that the transmission losses were also essentially as low as theory will allow, given that there was no guiding structure. For a graded index fiber of a given NA and radius, a, the expected fiber-to-fiber loss for propagation in a gap, s, filled by a material of index, n0, the following equation represents an expected gap loss relation:
Data from the above relation is presented for comparison in
Turning additionally to
As discussed above, the first precursor may include one or more partially fluorinated acrylate monomers, which are helpful for index matching of silica. Further, to obtain a desired elastomeric structure that maintains a desired shape, at least some portion of a multifunctional monomer may also be included. Additionally, to obtain a relatively low modulus, which is desirable to allow filling of gaps and surface irregularities during, for example, the mating of two fibers, some portion of the precursor may be a monomer that includes relatively flexible side chains and/or linkages between functional acrylate groups (e.g., generally reflected by having a relatively low glass transition temperature for the homopolymer, such as less than 25° C. and, more particularly, less than 0° C., for example). Furthermore, it may also be desirable that the monomers in the precursor be miscible in the proportions necessary to achieve the above-described attributes, and one or more of the monomers may be liquid at room temperature. Generally speaking, the photoinitiator to be included in the precursor may have a relatively high activity and may be soluble to at least 1%, and more particularly to about 2%, in the liquid formulation of monomers. Again, suitable examples of such monomers and photoinitiators are discussed above with reference to
The method further illustratively includes selectively curing the first precursor to form a core portion 148 of the index matching elastomeric solid layer 140 on the end face 133 to have an index of refraction n1 matching the index of refraction of the core 135, at Block 402. As discussed above, this may be done using electromagnetic (EM) radiation, such as UV light, for example (Block 402′). The method may also include removing uncured portions of the first precursor, at Block 403, and applying a second precursor for the curable index matching elastomeric solid layer 140 onto the end face 133 of the optical fiber 131 surrounding the core portion 148 of the index matching elastomeric solid layer, at Block 404. The second precursor may include similar components to those discussed above, but adjusted for the different index of refraction n2 of the cladding 137. If a graded index is to be produced, then a set of different monomers that have a difference in polymerization (or cross linking) rate and/or difference in index of refraction may be used (Block 404′), as will be appreciated by those skilled in the art. As noted above, an operation such as performing a soak at an elevated temperature may be used to provide the graded index structure, at Block 408′.
The method further illustratively includes curing the second precursor to form the cladding portion 149 of the index matching elastomeric solid layer 140 on the end face 133 to have an index of refraction n2 matching the index of refraction of the cladding, at Block 405, thus concluding the method illustrated in
In instances where the elastomeric solid layer 140 is to be employed in the interconnection of dissimilar optical fibers or waveguides, where the refractive indices of the respective core and cladding may differ between the fibers and/or waveguides to be connected, the core and cladding indices may advantageously lie between those of the interconnected fibers or waveguides. Choosing an intermediate value for the refractive index of the core of the elastomeric solid layer, as for example, the average of the refractive indices of the cores of the waveguides to be interconnected, can provide a reduction in the optical power lost in the interconnection. Likewise, choosing an intermediate value of the refractive index for the cladding as well as the core of the elastomeric solid layer can further reduce losses in the interconnection. Creating multiple layers of the elastomeric solid where the refractive index of the core and the cladding are progressively changed in a stepwise manner between the values of the two dissimilar fibers or waveguides can lead to even further decrease in loss, as will be appreciated by those skilled in the art.
A related method for making an index matching elastomeric solid layer 140 to be positioned onto the end face 133 of an optical fiber 131 is now described with reference to
A similar method for making an optical fiber device, such as the interconnection 30, is now described with reference to
Additional features of the invention may be found in the co-pending patent applications filed concurrently herewith and assigned to the Assignee of the present invention entitled A REPEATABLE OPTICAL WAVEGUIDE INTERCONNECTION INCLUDING AN INDEX MATCHING ELASTOMERIC SOLID LAYER AND RELATED METHODS, Ser. No. PCT/US10/54822; A REPEATABLE OPTICAL FIBER INTERCONNECTION INCLUDING AN INDEX MATCHING ELASTOMERIC SOLID LAYER PROVIDING CORE AND CLADDING INDEX OF REFRACTION MATCHING AND RELATED METHODS, Ser. No. PCT/US10/54827; OPTICAL FIBER SWITCH INCLUDING AN INDEX MATCHING ELASTOMERIC SOLID LAYER AND RELATED METHODS, Ser. No. PCT/US10/54851; and METHOD FOR MAKING AN OPTICAL FIBER DEVICE INCLUDING A CURABLE INDEX MATCHING ELASTOMERIC SOLID LAYER, Ser. No. PCT/US10/54887, the entire disclosures of which are hereby incorporated herein in their entirety by reference.
Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims.
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|US8231281 *||Nov 2, 2009||Jul 31, 2012||Harris Corporation||Repeatable optical waveguide interconnection including an index matching elastomeric solid layer providing core and cladding index of refraction matching and related methods|
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|U.S. Classification||385/22, 385/141, 385/53, 385/16|
|Cooperative Classification||G02B6/262, G02B6/3522, G02B6/3506, G02B6/32, G02B1/045, Y10T29/49885, G02B6/138|
|European Classification||G02B6/138, G02B6/35E4, G02B1/04D, G02B6/35D4|
|Nov 2, 2009||AS||Assignment|
Owner name: HARRIS CORPORATION, FLORIDA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SHACKLETTE, LAWRENCE WAYNE;REEL/FRAME:023457/0835
Effective date: 20091028